High-pressure fluid hydraulic propulsion system having means for avoiding shocks



Jan. 20, 1953 c, LDwm 2,625,913

HIGH-PRESSURE FLUID HYDRAULIC PROPULSION SYSTEM HAVING MEANS FOR AVOIDING SHOCKS Filed Jan. 18, 1947 2 SHEETS-SHEET I 1220622202 6 @0 6 lbaldwa' 22.

Jan. 20, 1953 c. P. BALDWIN 5,9

HIGH-PRESSURE FLUID HYDRAULIC PROPULSION SYSTEM HAVING MEANS FOR AVOIDING SHOCKS Filed Jan. 18 1947 x 2 SHEETSSHEET 2 a I E 9 O UE 56b 34 3/ 37 3 3 V J 12272672202: Ciyae RBlZ/dwa'zz.

Patented Jan. 20, i953 HIGH-PRESSURE FLUID HYDRAULIC PRO- PULSION SYSTEM HAVING MEANS FOR- AVOIDING SHOCKS Clyde P. Baldwin, Claremont, N. H., assignor to Joy Manufacturing Company, a corporation of Pennsylvania Application January 18, 1947, Serial No. 722,807

22 Claims. ((31.121-465) My invention relates to propulsion systems for vehicles, and more particularly to hydraulic propulsion systems having means for reducing the shocks imposed on the vehicles when fluid under high pressure is admitted to the ropulsion motor or motors thereof.

In the application of Harry A. Vanderzee and myself, Serial No. 578,084, now Patent No. 2,562,881, there is shown a propulsion system for a coal cutting machine in which a liquid under a relatively high pressure, several hundred pounds per square inch. is used to effect propulsion of the machine. The controlling system for the wheel drive of this machine provides for the requisite operations, but is de endent upon careful manipulation of the controls by the operator for the avoidance of shocks to the mechanism when. for example, starting the machine from rest, for cutting or tramming operation.

' It is an object of my invention to provide an improved hydraulic propulsion system for a vehicle such as, but without limitation thereto, a coal cutting machine. enabling the utilization of liquid under high pressure to drive the wheels of the vehicle, and providing, without dependence on the skill and care of the operator, for the avoidance of substantial shocks to the mechanism when liquid is admitted to the propulsion motors. It is another object of my invention'to provide an improved automatic valve mechanism, governed by the liquid supplied to effect propulsion of the wheel driving motors of a vehicle. for preventing the im osition of sudden shocks when the liouid is admitted to the conduits for transmission to the wheel driving motors. It is a further object of my invention to provide an im roved automatic control device for the lines leading to the hydraulic propulsion motors of a vehicle for initially admitting only a small quantity of fluid and then increasing the quantity'of fluid admitted at an appropriate rate until the maximum flow permitted by the master control valve is delivered, all in such manner as to avoid sudden jolting of the vehicle and shocks to the mechanism. Other objects and advantages of my invention will hereinafter more fully appear.

In the accompanying drawings, in which one embodiment of my invention is shown for purposes of illustration,

Fig. 1 is a fragmentary plan view of a kerf cutting machine in which the illustrative embodiment is incorporated.

2 .is. an elevational view of an automatic control .valve mechanism'forming a'portion of the-control system. Y I

Fig. 3 is a central sectional view through the mechanism of Fig. 2 on a plane parallel to'theplane of the sheet on which Fig. 2 appears and on an enlarged scale. j

Fig. 4 is a perspective view of a valve element;

Fig. 5 is a diagrammatic view showing the control system as a whole.

Referring to the drawings and first to Fig. '1, it will be observed that a kerf cutting machine I is illustrated as a setting for the invention. It will be understood, however, that other hydraulically propelled vehicles may equally well be used for the embodiment of the invention. The kerf cutting machine of Fig. 1 includes front propulsion wheels 2 having individual reversible driving motors 3 and 3 The machine has a cutting mechanism 4, supported, adjustable, and driven through mechanism illustrated in the aforementioned patent, the drive being by means of a. suitable motor 5. Propulsion of the vehicle. as well as numerous adjustments of its parts which do not enter into the present invention but which are described in saidjoint application, may be effected by dual pump mechanism 6;, including a large capacity pump 1 and a small capacity pump 8, both pumps. being driven by-al motor 9, herein distinct from the motor 5. The hydraulic fluid pumped by the small capacity pump 8 is under high pressure and has its distribution controlled by a valve box I0 having therein numerous valve devices of which .only

two are of present concern. This valve mecha nism is also illustrated in the application of said Vanderzee and myself last referred to. Thefluid pumped by the large capacity pump 1 is' also" under high pressure, and is controlled as Tater,

described.

Referring now to the diagram of Fig. 5, it will be observed that a tank or reservoir II suitably supported on the vehicle I is connected by a conduit l2, and branch conduits l3 and I 4 respectively, with the intakes of the large and small capacity pumps 1 and 8. The pump discharges are respectively connected to conduits l5 and IS. The discharge conduit 15 of the large capacity pump 1 leads to a conventional manually controllable four-way valve device H, which has its valve receiving bore appropriately connected by a conduit l8 back to the tank H. The conduit l8 communicates with the bore of the' valve mechanism I! at spaced points through ports [9 and 20. The large capacity pump discharge conduit 15 has a relief valve ill therein connected by a conduit 22'to the conduit l8; and this relief valve is set to open automatically in the event j the pressure in the system exceeds a--predeter-' mined maximum, thereby to prevent overloading of the system. Also leading from the valve receiving bore of the four-way valve device are conduits 25 and 26 which constitute the conduits through .which..fluid..is supplied from the large capacity pump! toeffect the propulsion of the truck by means of the wheel driving motors 3a and 3b.

The discharge conduit is from the small capacity pump leads to one end of the'valve box 10, while an exhaust or return line [2' is connected to the other end of the valve box I0. Conduits 21 and 28 lead from the valve box) and communicate with the conduits 25 and'ZB respec tively, and a valve device 29, shown in detail in the above mentioned application of said Vanderzee and myself, is provided for selectively connecting the small pump discharge or the exhaustin a direction to cause the vehicle to movetoward' the point of attach-ment of the cableassociated with the reel, but'to permit bypassing of the fluid without entering the reel driving motor when the vehicle is being moved in a direction away from the point of attachment of the cable, and to interconnect the supply and exhaust'connectionsfor the reel driving motor 50- that said motor may be Y turned without substantial resistance during the paying off of the cable. Conduits 33 and 34 lead from the 'valve box to the automatic control valvemechanism 3| and maybe controlled by, a reel motor control valve 35 of conventional form, fully described in the copending application mentioned, to enable reel drive without truck wheel drive. Leakage connections 36, Hand 38 extend from wheel driving motor 3a, reel driving motor 30, and wheel driving motor 3b .to the return line l2;

The :shock, preventer previously mentioned is generally designated 40. It includes a casing 41 having an axial bore 42 and end heads t3 and 4d. The conduit 25 leading from the valve box I! and adapted alsoto receive fluid from the small device 3| is connected by conduits 54 and 55 with the reel driving motor 30, and when fluid is supplied through the conduit 53 or through the conduit 33 to the valve device 3|, such fluid passes through the conduit 54 to the reel driving motor and drives the latter, then passes through the conduit 55 to the valve device 3| and 'to the conduit and from the latter through a branch conduit 55 into that one of the pair of alternatively supply and exhaust connections of the wheeldriving motor 3b which corresponds to the connection of driving motor 3a to which the conduit .53" leads, Before going on, it may be again mentioned that when fluid is supplied to the conduit 34, whether from the valve device 35 or as exhausted through the conduit 56 from the motor 3?), this fluid simply bypasses through the automatic control mechanism 3| to the line 33 without entering the reel driving motor 30, which at this time has its supply and exhaust connections in free communication with each "other.

Referring again to the T 52, the other side thereof is connected by aconduit 58 and a suitable check valve device 59 with the annular chamber it. As a result, it will be evident that fluid admitted to the chamber '55 from the conduit 25 cannot flow past the check valve device 55 into the conduitiifi, but fluid passing from the conduit 53 towards the chamber 35 may freely unseat the check'valve 59-and enter the chamber and pass 'throughthe conduit 25 to the valve mechanism l'l when -the-condu-it 25 is connected with the return line I8 through the port l9.

The annular chamber 49 isconnected' by-a short conduit SI with-a T' 62,- and from the'T 62 a branch 63, containing a cheolr valve device 64 corresponding *to the-check valve deviceii opens into the annular chamber 41.- Another conduit 65 leadsfrom the T 52 and this is connected by branches 66 and 61, each containing a manually adjustable stopva-lvefiB, with the others of the pairs of alternatively fluid supply and fluid 'eX- haust connectionsfor the: wheeldriving motors Sa-and 3b. Conduit Ei6-leads to the other alternatively supply and exhaustconnection for the wheel driving motorSa (note that the first of these supply and exhaust connections has the conduit 53' connected with it). The conduit 61 leads to the one of the alternatively supply and exhaust capacity pump throughythe conduit 21 opens into 7 an annularchamber 46 surrounding the valve bore A2 .near.one end of thellatter. Theconduit 26,- leadin from the valve'box l1 and adapted also to receive fluid from the small capacity pump through the conduit .28, opens intolan annular recess 41 surroundingthe valve bore 42 nearthe other end of thelatter. The annular recesses or chambers 45 andlll each communicate freely withthe valve bore. Two other annular chambers and 49surround and communicate freely with thevalve bore 42 near the central portion thereof, these chambers being separated from each .other-by an annular wall 50. The chamber lfl isconnected by a conduit 5| with a. T 52, one end of which communicates through aconduit 53-with=the conduit 33 which leads to the automatic controldevice 3|; and conduit 53 has a branch 53' which leads to one of a pair of alternativelyfiuid supply and 'iuid exhaust connectionsfor the wheel driving motor-3a, The'valve connections of the wheel driving motor 35 not connected with the conduit'fifi; As a result of these arrangements, it'will be understood that fluid may pass freely towards the chamber 4'. from the conduit 65, past the check valve device 64, but cannot flow in .the opposite. direction through the connection 63.

The heads 43 and 54 each have bosses 10 projecting therefrom and each has a bore H therein, the ends of these bores opening into the valve bore 42 through a projecting spring centering sleeve-like portion 13; Within the bore 42 there is slidably received a valve element 15 consisting of a central portion 76 constituting a close sliding fit for the bore 42, reduced spring-centering and movement-limitingjportions Tl at th'e'opposite sides of the portion 16, and further extended, further reduced portions .iS-at each end of-the valve member. The portions 18 coact with the bores H to form retarding cylinder and piston devices supplied with the operating liquid as'later noted. The valve member is'traversed throughout its length by a relatively small passage 19 which cooperates in the dash-pot functioning of the extensions #8 later described. Radial passages 80 open through each of :the portions-l8 into communication with the longitudinal pas sage 79 in positions to be closed, by passage within the bores in the portions 13 just as the valve 15 approaches its extreme positions of movement. Means is provided to enable progressive increases in flow area as the valve body is displaced from mid-position. This means may take the form'of tapering notches, either in the valve or in the walls of the valve casing. Herein, at the opposite ends of the main body portion I6 there are shown series of passages or notches 8| diminishing in depth towards the center of the body portion 16 and separated at their closest points by such a distance that in the mid-position of the valve element 15 neither of them communicates with either of the annular grooves or chambers and 49. w v

The valve element 15 is normally maintained, in the absence of the exertion of hydraulic shifting pressure thereon, in its central position by springs 82, 82, supported on thesleeve portions 13 and on the spring-centering, movement-limiting portions 11. The distance which the valve 15 may move from central position is controlled by the amount of free travel provided between the spring-supporting portions 11 and the sleevelike portions 13. The mode of operation may now be readily followed- When it is desired to effect propulsion of th coal cutting machin or other vehicle in a direction which will require the winding in of the current supply cable, the main valve device [1 may be actuated to effect the supply of liquid through the conduit 25 and to permit the return of liquid to the tank H through the conduit 26. The fluid passing through the conduit 25 will enter the chamber 46 and will be unable to pass the check valve device 59. It must accordingly, in order to attain access to the passage 53, do so by way of the chamber 48, and this it may do by displacing the valve element 15 to the right in Fig. 3. Since there is an unbalanced area on the left hand end of the head 16 and left hand portion 1! of the valve element 15, a force tending to move the valve to the right will be produced, but the rate at which valve movement will be possible will be controlled by the rate of displacement of fluid from the right hand cham-' ber H, and this rate will be controlled by the size of the passage 19. As the valve 15 commences to move toward the right in Fig. 3, the I left hand set of tapering notches 8| will be moved to provide initially very small, but progressively increasing communication between the chamber 46 and the chamber 48, and in the extreme position to th right of the valve l5, there will be free communication between the chambers 46 and 48 through an annular opening, past the end of the body 15 of the valve F5. The fluid passing first through the notches BI and then through the free annular opening last described will pass through the conduit 53 and will enter the wheel driving motor 3a directly through the conduit 53' and will effect rotation of motor 30.. Fluid will also pass through the automatic control device 3|, to the reel driving motor 30 by way of conduit 54, and, after actuating that motor, will pass through th conduit 55, again through the valve device 3], and by way of the conduits 34 and 56 into the'wheel driving motor 3b to drive the latter. Thus both wheel driving motors will be driven and the fluid, after doing its work in the'wheel driving motors, will "pass from'the 'motors 3a and 3b respectively'through the conduits 66 and '61" and the conduit*6'5,-free1y past 6. the check valve device B4 into-the chamber 41, and go by way of the conduit 26' and conduit l8 back to the tank. Accordingly it will be evident that instead of having movement of the valve mechanism I! to admit fluid to the conduit 25 result in the sudden delivery of liquid at several hundred pounds pressure to the wheel driving motors, without other restriction or delay than the care-of the operator will provide, therewill be automatically, through the controlled movement of the valve 15, a highly desirable initially small and suitably accelerated admission of fluid to the wheel driving motors and a substantially complete avoidance of shock. I

If it be desired to drive the wheels in the other direction, fluid may be admitted to the conduit 26, and, since it cannot pass through conduit 63 to conduit 65 directly, because of the check valve device 64, the fluid will have to mov the valve 15 to the left, and be admitted at a controlled rate to the conduit 6!, and from this conduit it will pass in part by way of conduit 65 and conduit 66 to motor 3a, from the latter through conduit 53' to conduit 53 and from the latter, past the check valve device 59, through chamber 46 and conduit 25, back to the valve device I1, and by way of port I9 and conduit l8 back to the reservoir I I. Another part of the fluid from c0n'- duit 65 will pass through conduit 61, through motor 3b, conduit 56, conduit 34, through the automatic valve device 3| without driving the reel, through a portion of conduit 33, and to conduit 53, and thence, with the other portion of the fluid, back to the reservoir ll.

When hydraulic fluid is supplied from the small capacity pump 8 under control of valve mechanism 29 shocks and jolts will also be avoided, because access of the fluid to the wheel driving motors will be possible only through the mechanism 49; When reel drive without wheel drive is desired, the valve mechanism 35 may be operated to effect this mode of operation, and the fluid for reel drive alone will not pass through the mechanism 40.

Referring again to Figure 3, it will be noted that the movement of the valve 15 in either di-frection is limited by engagement of the ends of the portions 11 with the stationary sleeve portions '13, that in such'extreme positions'of the valve one end of the valve body l6 will permit fluid flow past it to one of the annular chambers 48 or 49, and that because one or the other of the passages will be closed by reason of its position within one of the sleeve portions 13, there will be no flow between the supply and return lines through the conduit formed by 80, 19, 83, and so no-loss'of fluid without the doing of work thereby, when full supply to the motors is desired.

The areas on the ends of the valve body 16 outside the portions TL and the ends of the portions 1'! outside the further reduced portions 18 ob viously constitute throwing areasareas on which fluid acts to effect valve throwing.

All the fluid passing both to and from the wheel driving motors will pass through the mechanism 4!}, and only as the valve 15 is displaced at a controlled rate is the building up of flow rate to the wheel driving motors possible.

From the foregoing description it will be evident that I have provided an improved hydraulic system for the propulsion of vehicles by hig h pressure hydraulic fluid, and an improveda ofmatic valve mechanism" for pro' dinganj ini restricted flow of operatingfluid to' a" hydra life propulsion motor, with automatically increasing rateof fluid supply (with such rateautomatically controlled by :the built in dashpot arrangement) until the maximum desired rate is attained, and that such mechanism is so constructed and arrangedas to permit effective cooperation. with reversible motor drives.

While there is in this application specifically described one form which the invention may assume in practice, it will be understood that this form of the same is shown for purposes of illustration and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1: In combination, a source of hydraulic fluid underpressure, a motor for actuation by such fluid, operator controlled valve means controlling fluid supply to and fluid venting from said motor and associated conduit means between said valve means and said motor, and shiftable means for providing for an initially restricted, automatically increased freedom of communication between said valve means and said motor upon actuation of said operator controlled valve means to providefor relatively free flow of fluid past the same towards said motor and for relatively free communication between said motor and said operator controlled 'valve means upon actuation of the latter to provide for venting of fluid from said motor, said shiftable means including a valve device having a cylindrical central portion completely interrupting communication between said o erator controlled valve means and said motor past such portion in one position of the latter.

2. In combination, a source of hydraulic fluid under pressure, a motor for actuation by such fluid, operator controlled valve means controlling fluid supply to and fluid venting from said motor and associated conduit means between said valve means and said motor, and means interposed in said conduit means for providing for an initially restricted, automatically increased freedom of communication between said valve means and said motor upon actuation of said operator controlled valve means to provide for relatively free flow of fluid past the same towards said motor and for relatively free communication between said motor and said operator controlled valve means upon actuation of the latter to provide for venting of fluid from said motor, said means interposed in said conduit means including a valve device having a cylindrical central portion completely interrupting communication between said operator controlled valve means'and said motor past such portion in one position of the latter.

3. In combination, a source of hydraulic fluid under pressure, a motor for actuation by such fluid, operator controlled valve means controlling fluid supply to and fluid venting from said motor and associated conduit means between said valve means and said motor, and means having a surface thereon subjected to fluid moving towards said motor for effecting its own shifting to fluid supply efiecting position for providing for an initially restricted, automatically increased freedom of communication between said valve means and said motor upon actuation of said operator controlled valve means to provide for relatively free flow of fluid past the same towards said motor. and for relatively free communication between said motor and said operator controlled valve meansupon actuation of the latter to provide for ventingof fluid from said'motor, said 81 means..having the surface thereon as aforesaid including a vvalve device having a cylindrical central portion completely interrupting communication between said operator controlled valve means and said motor past such portion in one position of the latter.

4. In combination, a source of hydraulic fluid under pressure, a motor for actuation by such fluid, operator controlled valve means controlling fluid supply to and fluid venting from said motor and associated conduit means between said valve means and said motor, and means interposed in said conduit means and having a surface thereon subjected to fluid moving towards said motor for eflecting its own shifting to fluid supply effecting. position for providing for an initially restricted, automatically increased freedom of communication between said valve means and said motor upon actuation of said operator controlled valve means to provide for relatively free flow of fluid past the same towards said motor and for relatively free communication between said motor and said operator controlled valve means upon actuation of the latter to provide for venting of fluid from said motor, said means interposed in said conduit means including a valve device having a cylindrical central portion completely interrupting communication between said operator controlled valve means and said motor past such portion in one position of the latter.

5. In combination, a source of hydraulic fluid under pressure, at least one reversible motor, supply and return conduits connected with said source, conduits connected with said motor and adapted alternatively to constitute fluid supply and fluid exhaust lines, operator controlled valve means for connecting said conduits connected with said motor in communication selectively one with said supply conduit and the other with said return conduit, and vice versa, and valve mechanism connected with said conduits connected with said motor for initially restricting the flow therethrough towards said motor and thereafter providing automatically at a controlled rate for an increased flow capacity, said valve mechanism including a cylinder, a piston reciprocable therein, and means providing for a restricted rate of displacement of fluid from said cylinder for controlling the time interval between the establishments of conditions respectively for restricted flow and for initiation of increased flow.

6. In combination, a source of hydraulic fluid under pressure, at least one reversible motor, supply and return conduits connected with said source, conduits connected with said motor and adapted alternatively to constitute fluid supply and fluid exhaust lines, operator controlled valve means for connecting said conduits connected with said motor in communication selectively one with said supply conduit and the other with said return conduit, and vice versa, and valve mechanism connected with said conduits connected with said motor for initially restricting the flow therethrough towards said motor and thereafter providing automatically for an increased flow capacity at a controlled rate, said valve mechanism including a single valve member actuated in opposite directions by the fluid passing towards said motor to actuate the same in opposite directions.

7. In'combination, a source of hydraulic fluid under pressure, at least one reversible motor, supply and return conduits connected with said source, conduits connected with said motor and adapted alternatively to constitute fluid supply and, fluid exhaust lines, operator controlled valve means for connecting said conduits connected with said motor in communication selectively one with said supply conduit and the other with said return conduit, and vice versa, and valve mechanism connected with said conduits connected with said motor for initially restricting the flow therethrough towards said motor and thereafter providing automatically for an increased flow capacity, said valve mechanism including a single valve member actuated in opposite directions by the fluid passing towards said motor to actuate the same in opposite directions and said valve mechanism having dashpot means associated with it for controlling its rate of movement.

8. In combination, a source of hydraulic fluid under pressure, at least one reversible motor, supply and return conduits connected with, said source, conduits connected with said motor and adapted alternatively to constitute fluid supply and fluid exhaust lines, operator controlled valve means for connecting said conduits connected with said motor in communication selectively one with said supply conduit and the other with said return conduit, and vice versa, and valve mechanism connected with said conduits connected with said motor for initially restricting the flow therethrough towards said motor and thereafter providing automatically for an increased flow capacity, said valve mechanism including a single valve member actuated in opposite directions by the fluid passing towards said motor to actuate the same in opposite directions and said valve mechanism having dashpot means associated with it for controlling its rate of movement and having passage means of increasing flow area with increased valve displacement.

9. In combination, in an apparatus for providing for an initially restricted, automatically increasing flow passage area for operating fluid for a motor device, a casing having a valve receiving bore therein, a valve reciprocable in said bore, a pair of spaced chambers communicating with said bore at one side of a plane extending transversely thereof, another pair of spaced chambers communicating with said bore at the other side of said plane, said valve having a portion, of at least as great diameter at its longitudinal center as at its ends, for preventing, in the mid-position of said valve, communication between the chambers of either pair and movable to effect interconnection, past the ends of said portion and of a flow area increasing with displacement of said valve from mid-position, through said valve receiving bore of the chambers of one or the other of said pairs, said casing having connections for the supply of operating fluid from a source to the most remote chambers and for the venting of fluid from them, and said casing having connections communicating with the chambers nearest said plane and adapted for connection with alternative fluid supply and expair and movable in either direction from its mid-position to effect interconnection, of -a.,flow area increasing with displacement of said valve from mid-position, through said valve receiving bore of the chambers of one or the other of said pairs, said casing having connections for the sup ply of operating fluid from a source to the most remote chambers and forthe venting of fluid from them, and said casing further having connections communicating with the chambers nearest said plane and adapted for connection with alternative fluid supply and exhaust connections of a motor, and said portion of said valve being of at least as great diameter at its longitudinal center as at its ends.

11. In combination, inan apparatus for providing for an initially restricted, automatically increasing flow passage area for operating fluid for a motor device, a casing having a valvereceiving bore therein, a valve reciprocable in said bore, a pair of spaced chambers communicating with said bore at one side of a plane extending transversely thereof, another pair of spaced chambers communicating with said -b01eat the other side of said plane, said valve having a por tion preventing, in the mid-position of said valve, communication between the chambers. ot'said pairs and movable to efiect interconnection through said valve receiving bore: of the chambers of one or the other of said pairs, an"d said valve portion having thereon means forming flow passages of increasing efiective area as displace: ment from mid-position occurs, said casing having connections for the supply of operating fluid from a source to the most remote chambers and for the venting of fluid from them, and saidcasing further having connections communicating with the chambers nearest said plane and adapt: ed for connection with alternativev fluid supply and exhaust connections of a motor, and said portion of said valve being of at least as great diameter at its longitudinal center as at its ends.

12. In combination, in an apparatus for pro viding for an initially restricted, automatically increasing flow passage area for operating fluid for a motor device, a casing having a valve re ceiving bore therein, a valve reciprocable in said bore, a pair of spaced chambers communicating with saidbore at one side of a plane extending transversely thereof, another pair of spaced chambers communicating with said bore at the other side of said plane, said valve having a portion preventing, in the mid-position of said valve,

communication between the chambers of either pair and movable to eflect interconnection through said valve receiving bore of the chambers of one or the other of said pairs, means providing flow passages of increasing area, as valvefdisplacement occurs, between the chambers ofone or the other of said pairs, said casing" having connections for the supply of operating fluid from a source to the most remote ohambersand for the venting of fluid from them, and said casing further having connections communicating with the chambers nearest said plane and adapted for connection withalternative fluid supply and exhaust connections of a motor, and said p'ortion'of said valve at its longitudinal .center andfiatitjs ends having its periphery in a'fcom'mon' cylindrical surface. I 15f 13. In combination, in an apparatus forf providing for an initially restricted, automatically increasing flow passage area for operating fluid for a motor device, a casing having a valve receiving bore therein, a valve reciprocable in said bore, a pair of spaced chambers communieating with said bore atone side .ofaplane extendingtransversely thereof, another "pair of spaced chamberscommunicating with said bore at the other side of said plane, said valve having a portion preventing, in the mid-position of said valve, communication between the chambers of either pair and movable'to efiect interconnection, of a flow area increasing with displacement of said valve from mid-position, through said valve receiving bore of the chambers of on or the other of said pairs, said casing having connections forthe supply of operating fluid from a source to the most remote chambers and for the venting of fluid from them, and said casin having connections communicating with the chambers nearest said plane and adapted for connection with alternative fluid supply and exhaust connections of a motor, and means for establishing one-way flow connections between the chambers of each pair.

14, In combination, in an apparatusfor providing for an initially restricted, automatically increasing flowpassage area for operating fluid for a motor device, a casing having a valve receiving bore, therein, a valve reciprocable in said bore, a pair of spaced chambers communicating with said bore at one side of a plane extending transversely thereof, another pair of spaced chambers-communicating with said bore at the other side of said plane, said valve having a portion preventing, in the mid-position of said valve, communication between the chambers of either pair and movable. to eflect interconnection through said valve receiving bore of the chambers of one or the other of said pairs, means providing flow passages of increasing area, as valve displacement'occurs, betweenthe chambers of one or the other of said pairs and dashpot means associated with said valve for limiting its rate of movement, said casing having unitary connections for the supply of operating fluid from a source tothe most remote chambers and for the venting of fluid from them, and said casing further having connections communicating with the chambers nearest said plane and adapted for connection with alternative fluid supply and exhaust connections of a motor.

15. In combination, in an apparatus for providing for an initially restricted, automatically increasing flow passage area for operating fluid fora motor device, a casing having a valve receiving bore therein, a valve reciprocable in said bore; a pair of spaced chambers communicating with saidbore at one side of a plane extending transversely thereof, another pair of spaced chambers communicating with said bore at the other side of said plane, said valve having a portion preventing, in the mid-position of said valve, communication between the chambers of either pair and movable to effect interconnection through said valve receiving bore of the chambers of one or the other of said pairs, means providing flowpassages of increasing area, as

valve displacement occurs, between the chambers of one or the other of said pairs, and dashpot means associated with said valve for limiting its rate, of movement, said dashpot means including extensions on said valve and chambers in said casing and passage means connecting the opposite ends of said valve with each other, said casing having connections for the supply of operating fluid from a source to the most remote chambers of said pairs and for the venting of fluid from them, and said casing having connections communicating with the chambers nearest said plane and adapted'ior connection 12 with alternative fluid supply and exhaust connections of a motor.

16. In combination, in an apparatus for providing for an initially restricted, automatically increasing flow passage area for operating fluid for a motor device, a casing having a valve receiving bore therein, a valve reciprocable in said bore, a pair of spaced chambers communicating with said bore at one side of a plane extending transversely thereof, another pair of spaced chambers communicating With said bore at the other side of said plane, said valve having a portion preventing, in the mid-position of said valve, communication between the chambers of either pair and movable to effect interconnection through said valve receiving bore of the chambers of one or the other of said pairs, means providing flow passages of increasing area, as valve displacement occurs, between the chambers of one or the other of said pairs, and dashpot means associated with said valve for limiting its rate of movement, said dashpot means including extension on said valve and chambers in said casing and passage means connecting said last mentioned chambers in restricted communication with each other, said casing having connections for the supply of operating fluid from a source to the most remote chambers of said pairs and for the venting of fluid from them, and said casing having connections communicating with the chambers nearest said plane and adapted for connection with alternative fluid supply and exhaust connections of a motor.

17. In combination, in an apparatus for providing for an initially restricted, automatically increasing flow passage area for operating fluid for a motor device, a casing having a valve receiving bore therein, a valve reciprocable in said bore, a pair of spaced chambers communicating with said bore at one side of a plane extending transversely thereof, another pair of spaced chambers communicating with said bore at the other side of said plane, said valve having a portion preventing, in the mid-position of said valve, communication between the chambers of either pair and movable to effect interconnection through said valve receiving bore of the chambers of one or the other of said pairs, means providing flow passages of increasing area, as Valve displacement from mid-position occurs, between the chambers of one or the other of said pairs, and dashpot means associated with said valve for limiting its rate of movement, said dashpot means including extensions on said valve and chambers in said casing and passage means extending through said valve for connecting the opposite ends of said valve with each other, said casing having connections for the supply of operating fluid from a source to the most remote chambers of said pairs and for the venting of fluid from them, and said casing having connections communicating with the chambers nearest said plane and adapted for connection with alternative fluid supply and exhaust connections of a motor.

18. In combination, in an apparatus for providing for an initially restricted, automatically increasing flow passage area for operating fluid for a motor device, a casing having a valve receiving bore therein, a valve reciprocable in said bore, a pair of spaced chambers communicating with said bore at one side of a plane extending transversely thereof, another pair of spaced chambers communicating With said bore at the other side ofsaid plane; said valve having-a portion preventing, in the mid-position of said valve, communication between the chambers of either pair and movable to effect interconnection through said, valve receiving bore of the chambers of one or the other of said pairs, means providing flow passages of increasing area, as valve displacement from mid-position occurs, between the chambers of one or the other of said pairs, and dashpot means associated with said valve for limiting its rate of movement, said dashpot means including cooperating recesses and projections relatively movable upon valve movement and means for connecting said recesses in restricted communication with each other and, in the mid but not the extreme positions of said valve, with the valve receiving bore at both sides of said valve portion, said casing having connections for the supply of operating fluid from a source to the most remote chambers and for the venting of fluid from them, and said, casing having connections communicating with the chambers nearest said plane and adapted for connection with alternative fluid supply and exhaust connections of a motor.

19. In combination, a source of hydraulic fluid under pressure, a reversely rotatable motor for actuation by such fluid and having a pair of connections each serving alternatively as a supply passage for operating fluid and as an exhaust connection through which exhausting fluid is discharged as further fluid enters the motor through the other, operator controlled valve means and associated conduit means for effecting operator controlled supply of fluid from said source to one or the other of said connections to said motor to efiect operation of said motor selectively in either direction, and exhaust, during motor operation and through the connection not serving for fluid supply, of fluid from said motor, irrespective of the direction of operation of said motor, and valve means interposed in said conduit means for providing, irrespective of the direction of rotation of said motor, an initially restricted, automatically increasing freedom of communication between said operator controlled valve means and said motor upon actuation of said operator controlled valve means to provide for relatively free flow of fluid past the same, said last recited valve means having, to control the rate of increase of freedom of communication, retarding means including cylinder and piston mechanism providing chambers from which fluid must be displaced as increasing freedom of communication occurs and having restricted communication with said source when said operator controlled valve means supmechanism connected with said conduits connected with said motor for initially restricting the flow therethrough towards said motor and thereafter providing automatically for an increased flow capacity, said valve mechanism including a single valve member having thereon throwing areas spaced from its ends and alternatively subjected to fluid passing towards said motor to actuate the same in opposite directions and further having portions constituting dash pot elements for controlling its rate of movement.

21. In combination, a source of hydraulic fluid under pressure, at least one reversible motor, supply and return conduits connected with said source, conduits connected with said motor and adapted alternatively to constitute fluid supply and fluid exhaust lines, operator controlled valve means for connecting said conduits connected with said motor in communication selectively one with said supply conduit and the other with said return conduit, and vice versa, and valve mechanism connected with said conduits connected with said motor for initially restricting the flow therethrough towards said motor and thereafter providing automatically for an increased flow capacity, said valve mechanism including a single valve member having thereon throwing areas spaced from its ends and alternatively subjected to fluid passing towards said motor to actuate the same in opposite directions and further having portions at its ends constituting dash pot elements for controlling its rate of movement.

22. In combination, a source of hydraulic fluid under pressure, at least one reversible motor, supply and return conduits connected with said source, conduits connected with said motor and adapted alternatively to constitute fluid supply and fluid exhaust lines, operator controlled valve means for connecting said conduits connected with said motor in communication selectively one with said supply conduit and the other with said return conduit, and vice versa, and valve mechanism connected with said conduits connected with said motor for initially restricting the flow therethrough towards said motor and thereafter providing automatically for an increased flow capacity, said valve mechanism including a single valve member having thereon throwing areas spaced from its ends and alternatively subjected to fluid passing towards said motor to actuate the same in opposite directions and further having portions at its ends constituting dash pot elements for controlling its rate of movement, said valve member further having a passage extending through the same from end to end.

CLYDE P. BALDWIN.

REFERENCES CITED The following references are of record in the file of this patent:

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